The lyme disease spirochete, Borrelia burgdorferi, has a unique morphlogy. Outer most is a menbrane sheath, and within this sheath is a helical shaped cell cylinder. At each end of the cell cylinder, bacterial flagella-like organelles, called periplasmic flagella, are attached. Genetic analysis has shown that these organelles are involved in the motility and shape of spirochetes. In addition, several lines of evidence indicate that these periplasmic flagella propel the organisims by rotation in manner similar to bacterial flagella. The thrust of our research is centered on determining exactly how these spirochetes swim and in what direction, i.e. clockwise or counter-clockwise. To answer these questions we are using the BMIRR to conduct high resolution 3D HVEM tomographic studies of periplasmic flagella.